1. Field of the Invention
The subject invention relates generally to portable turntables for use in microwave ovens and specifically to switch assemblies for such turntables for controlling rotational movement.
2. The Prior Art
Portable turntables for microwave ovens are known and are commonly available in consumer markets. Such devices typically comprise a stationary base, a rotatable platform mounted to the base, and a drive motor. An on/off switching mechanism is generally provided to control the rotational movement of the platform relative to the base.
Achievement of a suitable on/off switch for microwave turntables has proven illusive. Such switching mechanicms must be convenient to operate, fail-safe, and compact in spacial dimension so as to fit within the smaller microwave oven cavities. Further, the switching mechanism must smoothly act to move the turntable in and out of its rotational mode of operation without requiring manual manipulation.
Various approaches at attaining an acceptable on/off switch for such turntables have been tried. For example, U.S. Pat. No. 4,434,343 teaches a rotatable platform component having a downward peripheral rim flange which incorporates inward directed gear teeth spaced therealong. A slidable lock is provided which extends below the downward rim flange and axially moves inward and outward whereby moving a rectangular meshing tooth in and out of engagement with the rim flange gear teeth.
While the above switch mechanism works well, it has certain deficiencies which prevent it from achieving all of the above-discussed performance requirements. First, operation of a sliding switch is cumbersome and can result in the turntable being pushed or pulled in jarring fashion. Undesired spillage of food stuffs supported by the turntable can result. Further, sliding actuation can cause the tooth of the sliding mechanism to stub against the gear teeth along the rim flange. Overcoming the impasse would require manual jogging of the lock mechanism and/or the turntable platform. However, such a procedure in the small confines of a microwave oven is awkward and can, again, result in foodstuff spillage.